GERT is a one-armed single-center phase I/II trial. In a first step, dose-escalation of TMZ from 50 mg/m2 to 75mg/m2 together with radiotherapy and cetuximab will be performed. Should safety be proven, the phase II trial will be initiated with the standard dose of 75mg/m2 of TMZ. Cetuximab will be applied in the standard application dose of 400mg/m2 in week 1, thereafter at a dose of 250mg/m2 weekly. A total of 46 patients will be included into this phase I/II trial.